The importance of monitoring key aroma compounds as food characteristics to solve sample classification and authentication is increasing. The rhizome of Polygonatum sibiricum (PR, Huangjing in Chinese) has great potential to serve as an ingredient of functional foods owing to its tonic effect and flavor properties. In this study, we aimed to characterize and classify PR samples obtained from different processing levels through their volatile profiles and flavor properties by using electronic nose, electronic tongue, and headspace gas chromatography-mass spectrometry. Nine flavor indicators (four odor indicators and five taste indicators) had a strong influence on the classification ability, and a total of 54 volatile compounds were identified in all samples. The traditional Chinese processing method significantly decreased the contents of aldehydes and alkanes, while more ketones, nitrogen heterocycles, alcohols, terpenoids, sulfides, and furans/pyrans were generated in the processing cycle. The results confirmed the potential applicability of volatile profiles and flavor properties for classification of PR samples, and this study provided new insights for determining the processing level in food and pharmaceutical industries based on samples with specific flavor characteristics.

Introduction: Typhae pollen (TP) has been used as an anticoagulant in traditional Chinese medicine and throughout Asia. Typhae Pollen Carbonisata (TPC), a processed product of TP, has hemostatic properties. TPC is produced by frying TP, and the degree of processing can be judged by the colour change from yellow to brown. Objective: To establish a novel method for quality assessment of TPC and discriminate TPC from underdone products and overdone products. Methodology: The Commission Internationale de l'Eclairage (CIE) L * a * b * colour space values of TP and TPC were measured to establish the colour model of TPC. Ultra-performance liquid chromatography was developed for fingerprinting. Thrombin activity promoting rates, clotting time, and bleeding time illustrated the difference in the hemostatic effect of the processed products. Chemometric approaches were performed to reveal the correlation between components and colour values or thrombin activity. Results: Reference ranges of colour values and mathematical functions of TPC were established. The developed method was found to be fast, economic, sensitive, and stable. Fingerprints and thrombin activity in conjunction with partial least squares (PLS) demonstrated that peaks 2, 4, 7, 30, and 36 (isorhamnetin) were the main contributors for colour values and hemostatic activity of TPC. Conclusions: TPC and its unqualified products can be effectively distinguished based on chromaticity analysis, which provides a powerful tool for the comprehensive evaluation of the quality of Chinese herbal medicines.

The rhizome of Polygonatum sibiricum Red. (PR, Huangjing in Chinese) has served as traditional medicine and foodstuff in China for over 2000 years. However, due to its irritating effect on the throat, Huangjing must be processed before clinical use. People have been exploring to determine the processing level of traditional Chinese medicine in an accurate tool. The evaluation of PR processing levels based on macroscopic and microscopic characteristics has not yet been performed. This study aimed to provide a convenient method to determine the level of PR processing by monitoring the changes in color and crystal inclusion. According to the Chinese Pharmacopeia (2020 edition), macroscopic, micromorphological, and microscopic observations were performed with a polarized light microscope. Color quantization based on the CIE L * a * b * color system using a CM-2300d colorimeter. Color parameters h , L * , and ΔE * had a significant influence on the differentiation ability. The inner transverse section of PR samples gradually turned into moist black with specular luster, which was consistent with the traditional identification of "brightness like oil and color like black lacquer." The change rate of the needle crystal morphology increased with the processing level, and the change rate of the needle crystal of the fifth product was over 90%. Combined with the correlation analysis, needle-like crystals were related to color parameters and could be used as an alternative marker to discriminate PR samples from different processing levels. The results confirmed the potential applicability of macroscopic and microscopic features for the classification of PR samples with different processing levels. Research Highlights1. Color parameters h , L * , and ΔE * had a significant influence on the differentiation ability.2. Micromorphological results were consistent with the traditional identification.3. High correlations were found between color parameters and needle-like crystals.